Former RUSADA general director Ramil Khabriev told the Tass news agency he believed Kamaev had died at home after feeling pain in his chest following a session of cross-country skiing.

Kamaev and Khabriev resigned in December as the Russian Sports Ministry pushed for the agency to carry out reforms under new leadership. That was a month after RUSADA was stopped from conducting drug tests when the World Anti-Doping Agency declared it non-compliant with global anti-doping rules.

A WADA commission accused RUSADA of covering up cases of doping by leading Russian athletes, giving them advance knowledge of supposedly surprise tests and allowing banned athletes to continue competing.

The WADA report led the International Association of Athletics Federations to suspend Russia's track and field program from global competition, leaving its athletes in danger of missing this year's Olympics in Rio de Janeiro.

Kamaev was the day-to-day head of RUSADA operations from 2011 until his resignation in December. The day after the WADA commission's report emerged accusing RUSADA of covering up doping, he made a vehement defence of the organization, saying it had been fighting drug use effectively, and claiming that the commission produced a biased report based on unreliable testimony from athletes who had been caught doping.

"Some of the issues have a particular acuteness and are, if you like, politicized," he said at the time.

Accusations that agents from Russia's FSB security service infiltrated the doping lab for the 2014 Winter Olympics in Sochi were the product of an "inflamed imagination," he added.

Rune Anderson, chair of the IAAF inspection team's anti-doping task force, spoke with the CBC's Corinne Seminoff in Moscow on Moinday, but declined to comment on whether Kamaev was under investigation.

The task force is expected to issue their report at a IAAF coucil meeting sometime in early March.

Kamaev's death came less than two weeks after another former RUSADA figure. Founding chairman Vyacheslav Sinev, who left the agency in 2010, died on Feb. 3, according to RUSADA, which didn't elaborate.